The present invention relates to material removing tools, such as boring or milling tools, and more particularly to improvements in rotary supports or holders for the knives, cutters or analogous material removing implements of such tools.
It is already known to interpose an adapter between a material removing knife or cutter and a rotary shank which is insertable into the chuck of a boring, drilling or an analogous machine so that it can transmit torque to the knife or cutter through the medium of the adapter. The adapter is connected to the front end face of the shank by at least one screw so that it can be readily separated from the shank but is capable of transmitting torque to the knife or cutter which is carried thereby and is held in axial alignment with the shank. The adapter and the shank are formed with aligned chip-removing grooves. It is also known to provide the front end of the shank with a forwardly extending projection or stub which extends into a complementary socket of the adapter. The aforementioned screw which connects the adapter to the shank extends through aligned radially extending bores provided in that portion of the adapter which surrounds the socket and in the stub of the shank.
In a conventional tool holder of the above-outlined character, the front end face of the shank is formed with two eccentric plugs which extend into complementary axially parallel bores in the rear end face of the adapter. The adapter is formed with additional bores which extend radially of the just mentioned axially parallel bores and receive screws serving to secure the adapter to the respective plugs at the front end of the shank. The remainder of the front end face of the shank is disposed in a radial plane and is smooth. Such mode of connecting the shank with the adapter is not entirely satisfactory because the adapter is likely to vibrate when the tool is in actual use. Moreover, the connection which consists exclusively of two eccentric plugs is not sufficiently resistant to bending stresses which arise when the cutting edge or edges of the knife or knives penetrate into the material of a workpiece.